1. Field of the Invention
The present invention relates to a slide position sensor and a press machine.
2. Description of the Related Art
A press machine has conventionally been used for drawing a workpiece. The press machine of the kind is provided with a slide position sensor for sensing a position of a slide to which an upper die is attached (see, document: JP-A-09-314395, FIG. 7).
The slide position sensor disclosed in the above document includes a scale provided on a slide that is lifted up and down and a sensing device provided to a fixed upright. The sensing device senses the scale to obtain a position of the slide.
Here, the scale provided to the slide and the sensing device provided to the upright are disposed close to each other in the press machines of the kind. Besides, an eccentric load may be generated in the press machine during drawing process, which may cause an inclination of the slide.
In such a case, the disclosed slide position sensor may not tolerate the inclination of the slide, and the sensing device may be contacted with the scale or excessively spaced apart from the scale. In this case, the position of the slide is not precisely obtained. In addition, the sensing device or the scale may even be damaged because of the contact between the sensing device and the scale.